“Ziplines” are gravity-based cable rides generally used to transport people for various purposes including recreational thrill rides, forest canopy tours, and challenge courses. A typical zipline includes a stranded steel wire cable or fibre rope suspended between two supports, platforms at each support for launching and landing riders, and pulley blocks and harnesses to support and transport riders along the cable.
FIG. 1 depicts a typical zipline system in which wire rope main cable 12 is suspended between supports 14, 18 which may be constructed of wood, steel, aluminum or any other structurally suitable material. Trees, boulders or cliffs may alternatively function as supports 14, 18. Launch platform 16 is constructed on or surrounding support 14, and landing platform 20 is constructed on or surrounding support 18. Either or both of platforms 16, 20 may be (and typically are) fixed or mounted at elevated locations on supports 14, 18 respectively. Each platform 16, 20 may be equipped with a ramp or steps 28 to assist in launching and landing of riders. Platforms 16, 20 are typically also equipped with suitable safety railings and access control gates. Platforms 16, 20 may be suspended relative to supports 14, 20 to facilitate raising or lowering of platforms 16, 20 (e.g. via suitable motorized winches) in order to periodically adjust the tension of cable 12. Overhead supports 17, 21, are optionally mounted to supports 14, 18, respectively.
Rider 32 begins by donning harness 33 supplied by the zipline operator. Harness 33 includes a short primary tether 34 and an optional back-up safety tether 35 (FIG. 2) both of which are securely fastened to pulley block 30. After donning harness 33, rider 32 ascends launch platform 16, where the zipline operator's personnel couple pulley block 30 to cable 12, such that pulley block 30 may roll smoothly along cable 12. Rider 32 is released under the control of the zipline operator's personnel. More particularly, pulley block 30 rolls along cable 12 toward landing platform 20 (i.e. from left to right as viewed in FIG. 1) with rider 32 suspended beneath cable 12 by harness 33 and tether 34.
Rider 32 must reach and be braked and arrested at landing platform 20. If rider 32 is not properly braked upon arrival at landing platform 20, the moving rider may collide with support 18, with landing platform 20 or with persons or objects thereon. If rider 32's motion is not properly arrested upon arrival at landing platform 20, rider 32 may roll back down to the nadir of cable 12. Similarly, if rider 32 is not carried along cable 12 with sufficient velocity, rider 32 may slow down, stop short of landing platform 20, and roll back down to the nadir of cable 12. In either case, the zipline operator's personnel must rescue rider 32 from the nadir of cable 12. The rescue technique is well known and straightforward, and need not be described here. But, to avoid potentially time-consuming and somewhat labour intensive rescue operations, the slope of cable 12 (the vertical distance between platforms 16, 20), the cable's sag (the vertical distance between cable 12 at mid-span and a chord drawn between supports 14, 18) and the cable's tension are adjusted to achieve a reasonable transit time at sufficient velocity along cable 12 to enable rider 32 to reach landing platform 20.
If the zipline is particularly steep, the rider's speed may be quite high, necessitating control of the rider's speed as well as effective braking of the rider. In some cases it is desirable to control a rider's movement throughout the ride, including the capability to brake and stop the rider at any point throughout the ride. Suitable apparatus and techniques for controlling the movement, speed and acceleration of a zipline rider are discussed below.
The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.